U.S. patent application number 13/502024 was filed with the patent office on 2012-08-09 for organic electroluminescent light source device.
Invention is credited to Hiroyasu Inoue.
Application Number | 20120200221 13/502024 |
Document ID | / |
Family ID | 43876193 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120200221 |
Kind Code |
A1 |
Inoue; Hiroyasu |
August 9, 2012 |
ORGANIC ELECTROLUMINESCENT LIGHT SOURCE DEVICE
Abstract
An organic electroluminescent light source device including a
first transparent electrode layer, a light-emitting layer, a second
transparent electrode layer, and a reflective layer having a
reflective surface, in this order from a light-emitting surface
side, and further including a structural layer X that is provided
between the second transparent electrode layer and the reflective
surface and is in contact with the reflective surface, wherein the
reflective surface has a concavo-convex structure, the
concavo-convex structure has a plurality of concavo-convex
structure units formed of depressions or protrusions, and a
refractive index n of the structural layer X, an inclination angle
.theta..times.1 (.degree.) of the concavo-convex structure units,
and a mean inclination angle .theta..times.2 (.degree.) of the
concavo-convex structure at the reflective surface satisfy
.theta..times.1.ltoreq.sin.sup.-1(1/n) and {90-sin.sup.-1(1/n)
}/3.ltoreq.0.times.2.ltoreq.sin.sup.-1(1/n).
Inventors: |
Inoue; Hiroyasu; (Tokyo,
JP) |
Family ID: |
43876193 |
Appl. No.: |
13/502024 |
Filed: |
October 13, 2010 |
PCT Filed: |
October 13, 2010 |
PCT NO: |
PCT/JP2010/067958 |
371 Date: |
April 13, 2012 |
Current U.S.
Class: |
313/504 |
Current CPC
Class: |
H01L 51/5275 20130101;
G02B 5/0231 20130101; H01L 51/0096 20130101; H01L 51/5271 20130101;
G02B 5/0289 20130101 |
Class at
Publication: |
313/504 |
International
Class: |
H05B 33/22 20060101
H05B033/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2009 |
JP |
2009-237169 |
Claims
1. An organic electroluminescent light source device comprising a
first transparent electrode layer, a light-emitting layer, a second
transparent electrode layer, and a reflective layer having a
reflective surface, in this order from a light-emitting surface
side, and further comprising a structural layer X that is provided
between the second transparent electrode layer and the reflective
surface and is in contact with the reflective surface, wherein the
reflective surface has a concavo-convex structure, the
concavo-convex structure has a plurality of concavo-convex
structure units formed of depressions or protrusions, and a
refractive index n of the structural layer X, an inclination angle
.theta..times.1 (.degree.) of the concavo-convex structure units,
and a mean inclination angle .varies..thrfore.2 (.degree.) of the
concavo-convex structure at the reflective surface satisfy the
following expressions (1) and (2): .theta..times.1sin.sup.-1(1/n)
(1) {90-sin.sup.-1(1/n)}/3.ltoreq..theta..times.2sin.sup.-1(1/n)
(2).
2. The organic electroluminescent light source device according to
claim 1, wherein the refractive index n of the structural layer X
and the mean inclination angle .theta..times.2 (.degree.) of the
concavo-convex structure at the reflective surface satisfy the
following expression (3):
{90-sin.sup.-1(1/n)}/2.ltoreq..theta..times.2sin.sup.-1(1/n)
(3).
3. The organic electroluminescent light source device according to
claim 1, wherein the refractive index n of the structural layer X
and the mean inclination angle .theta..times.2 (.degree.) of the
concavo-convex structure at the reflective surface satisfy the
following expression (4):
({90+sin.sup.-1(1/n)}/4)-5.ltoreq..theta..times.2({90+sin.sup.-1
(1/n)}/4)+5(4).
4. The organic electroluminescent light source device according to
claim 1, wherein the concavo-convex structure units of the
reflective surface have a pyramid or prismoid shape.
5. The organic electroluminescent light source device according to
claim 1, wherein the concavo-convex structure has depressions
provided apart from each other as concavo-convex structure units
and flat gap portions between adjacent depressions.
6. The organic electroluminescent light source device according to
claim 1, wherein the reflective layer is a stacked body of a first
metal layer including a first metal and a second metal layer
including a second metal which is different from the first
metal.
7. The organic electroluminescent light source device according to
claim 1, further comprising a light diffusion layer provided on a
light-emitting surface side of the reflective layer.
Description
FIELD
[0001] The present invention relates to an organic
electroluminescent (hereinafter sometimes referred to as "organic
EL") light source device.
BACKGROUND
[0002] An organic EL light source device is an element in which an
organic light-emitting layer is provided between a plurality of
electrode layers to electrically obtain light emission. Organic EL
light source devices have been studied regarding its use as a
display element in place of a liquid crystal cell. Further, the use
of organic EL light source devices as a surface light source, such
as a backlight for flat-type illumination or for a liquid crystal
display device, that utilizes the characteristics of a high
luminous efficiency, low voltage drive, light weight, low cost and
the like, is also being studied.
[0003] One issue when using an organic EL light source device as a
surface light source is how to efficiently extract light in a
useful form from the organic EL light source device. For example,
although the light-emitting layer of the organic EL light source
device itself has a high luminous efficiency, the light amount
decays due to interference and the like in the layers during the
light passes through the layered structures of the device and
emitted therefrom. Thus, this loss of light needs to be as small as
possible.
[0004] As a method for increasing light extraction efficiency, for
example, Patent Literature 1 discloses improvement of the overall
brightness by suppressing the brightness in the frontal
direction(0.degree.) of the device and increasing the brightness at
angles of 50 to 70.degree..
CITATION LIST
Patent Literature
[0005] Patent Literature 1: Japanese Patent Application Laid-Open
No. 2004-296423
SUMMARY
Technical Problem
[0006] However, there is a need for further improvement in light
extraction efficiency of a light source device.
[0007] Therefore, it is an object of the present invention to
provide an organic EL light source device that has a higher light
extraction efficiency.
Solution to Problem
[0008] As a result of research by the present inventor to solve the
aforementioned problem, the present inventor has found out that the
aforementioned problem could be resolved by, in an organic EL light
source device, using transparent electrodes for both of a pair of
electrodes forming a light-emitting element, providing a reflective
layer having a reflective surface that has a concavo-convex
structure, and setting a relationship between the inclination angle
of this concavo-convex structure and the refractive index of a
structural layer provided in contact with the reflective surface to
satisfy a specific expression, thereby completing the present
invention.
[0009] Accordingly, the present invention provides the following
[1] to [7].
[0010] [1] An organic electroluminescent light source device
comprising a first transparent electrode layer, a light-emitting
layer, a second transparent electrode layer, and a reflective layer
having a reflective surface, in this order from a light-emitting
surface side, and further comprising a structural layer X that is
provided between the second transparent electrode layer and the
reflective surface and is in contact with the reflective surface,
wherein [0011] the reflective surface has a concavo-convex
structure, [0012] the concavo-convex structure has a plurality of
concavo-convex structure units formed of depressions or
protrusions, and [0013] a refractive index n of the structural
layer X, an inclination angle .theta..times.1 (.degree.) of the
concavo-convex structure units, and a mean inclination angle
.theta.2 (.degree.) of the concavo-convex structure at the
reflective surface satisfy the following expressions (1) and
(2):
[0013] .theta..times.1.ltoreq.sin.sup.-1(1/n) (1)
{90-sin.sup.-1(1/n)}/3.ltoreq..theta..times.2.ltoreq.sin.sup.-1(1/n)
(2).
[0014] [2] The organic electroluminescent light source device
according to [1], wherein the refractive index n of the structural
layer X and the mean inclination angle .theta..times.2(.degree.) of
the concavo-convex structure at the reflective surface satisfy the
following expression (3):
{90-sin.sup.-1(1/n)}/2.ltoreq..theta..times.2.ltoreq.sin.sup.-1(1/n)
(3)
[0015] [3] The organic electroluminescent light source device
according to [1] or [2], wherein the refractive index n of the
structural layer X and the mean inclination angle 74 .times.2
(.degree.) of the concavo-convex structure at the reflective
surface satisfy the following expression (4):
({90+sin.sup.-1(1/n)}/4)-5.ltoreq..theta..times.2.ltoreq.({90+sin.sup.-1-
(1/n)}/4)+5 (4).
[0016] [4] The organic electroluminescent light source device
according to any one of [1] to [3], wherein the concavo-convex
structure units of the reflective surface have a pyramid or
prismoid shape.
[0017] [5] The organic electroluminescent light source device
according to any one of [1] to [4], wherein the concavo-convex
structure has depressions provided apart from each other as
concavo-convex structure units and flat gap portions between
adjacent depressions.
[0018] [6] The organic electroluminescent light source device
according to any one of [1] to [5], wherein the reflective layer is
a stacked body of a first metal layer including a first metal and a
second metal layer including a second metal which is different from
the first metal.
[0019] [7] The organic electroluminescent light source device
according to any one of [1] to [6], further comprising a light
diffusion layer provided on a light-emitting surface side of the
reflective layer.
Advantageous Effects of the Invention
[0020] The light source device according to the present invention
has a high light extraction efficiency while also being highly
durable even when having a simple, thin structure. Therefore, the
light source device of the invention is useful as the light source
for a backlight for use in a liquid crystal display device, an
illumination device and the like.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a first embodiment of the present
invention.
[0022] FIG. 2 is an enlarged perspective view schematically
illustrating the concavo-convex structure portion 141 of a
reflective portion composite substrate 140 illustrated in FIG.
1.
[0023] FIG. 3 is a partial cross-sectional view illustrating a
concavo-convex structure unit 14Z of the reflective portion
composite substrate 140 illustrated in FIG. 2 along a plane that
passes through the line 2a parallel to the bottom edge 14E and that
is parallel to the Z axis direction.
[0024] FIG. 4 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a second embodiment of the present
invention.
[0025] FIG. 5 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a third embodiment of the present
invention.
[0026] FIG. 6 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a fourth embodiment of the present
invention.
[0027] FIG. 7 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a fifth embodiment of the present
invention.
[0028] FIG. 8 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a sixth embodiment of the present
invention.
[0029] FIG. 9 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a seventh embodiment of the present
invention.
[0030] FIG. 10 is a partial cross-sectional view schematically
illustrating an example of reflection of light at a reflective
surface.
[0031] FIG. 11 is a perspective view schematically illustrating a
modified example of the reflective portion composite substrate 140
having the concavo-convex structure portion 141 of the first
embodiment.
[0032] FIG. 12 is a partial cross-sectional view illustrating a
concavo-convex structure unit 24Z of the reflective portion
composite substrate 240 illustrated in FIG. 11 along a plane that
passes through the line 3a parallel to the bottom edge 24E and that
is parallel to the Z axis direction.
[0033] FIG. 13 is a partial cross-sectional view schematically
illustrating a modified example of the concavo-convex structure
unit 14Z of the reflective portion composite substrate 140 having
the concavo-convex structure portion 141 in the first
embodiment.
[0034] FIG. 14 is a partial cross-sectional view schematically
illustrating a modified example of the concavo-convex structure
unit 14Z of the reflective portion composite substrate 140 having
the concavo-convex structure portion 141 in the first
embodiment.
[0035] FIG. 15 is a partial cross-sectional view schematically
illustrating a modified example of the concavo-convex structure
unit 14Z of the reflective portion composite substrate 140 having
the concavo-convex structure portion 141 in the first
embodiment.
[0036] FIG. 16 is a perspective view schematically illustrating
another modified example of the reflective portion composite
substrate 140 having the concavo-convex structure portion 141 in
the first embodiment.
[0037] FIG. 17 is a perspective view schematically illustrating
another modified example of the reflective portion composite
substrate 140 having the concavo-convex structure portion 141 in
the first embodiment.
[0038] FIG. 18 is a graph illustrating a result of study in Example
2.
[0039] FIG. 19 is a graph illustrating a result of study in
Reference Example 1.
DESCRIPTION OF EMBODIMENTS
[0040] Preferred embodiments of the present invention will now be
described with reference to the drawings. In each drawing, the
shape, size, and arrangement of the components are illustrated
merely in a schematic manner that allows understanding of the
present invention. The present invention is not limited to the
following description. Further, the respective components may be
appropriately changed within the scope of the claims and equivalent
thereto. In the drawings used in the following description,
components that are the same are denoted with the same reference
numerals, and repetitive descriptions may be omitted.
First Embodiment
[0041] FIG. 1 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a first embodiment of the present invention.
Unless otherwise specified, in the present application the light
source device will be described assuming that its light-emitting
layer is horizontally placed with the light-emitting surface of the
device facing upwards. Therefore, unless otherwise specified, in
the following description the expression "horizontal plane" is the
plane that is parallel to the main plane of the light-emitting
layer, the upper side of the light source device is the
light-emitting surface side, and the lower side is the side
opposite to the light-emitting surface. This is simply for the sake
of convenient explanation of the positional relationships. The
placement of the light source device when the light source device
is used is not at all limited to this horizontal placement
state.
[0042] Further, in the following description, the light incident
angle, the light emission angle, the light reflection angle, and
the critical angle of light at an interface are the angles between
the incident light, emitting light, or reflected light and the
normal direction of the interface. In addition, in the following
description, the inclination angle of the concavo-convex structure
is the angle between a surface of the concavo-convex structure and
the horizontal plane. The normal direction with respect to the
horizontal plane is sometimes simply referred to as the "Z axis
direction".
[0043] In FIG. 1, a device 100 includes a substrate 101, a
light-emitting element 120 that is provided on a lower side of the
substrate 101, a sealing substrate 102 that is provided on a lower
side of the light-emitting element 120 with a sealing layer 131
arranged therebetween, and a reflective portion composite body 144
that is provided on a lower side of the sealing substrate 102 with
an adhesion layer 132 arranged therebetween. The sealing layer 131,
the sealing substrate 102, and the substrate 101 seal the
light-emitting element 120. Consequently, degradation of the
light-emitting element 120 due to contact with oxygen, moisture and
the like in the exterior air when the light source device 100 is
used can be prevented.
[0044] The reflective portion composite body 144 includes a
reflective portion composite substrate 140 with a concavo-convex
structure portion 141 formed thereon, and a reflective layer 142
that is provided on the concavo-convex structure portion 141. The
reflective layer 142 is adhered to the lower surface of the sealing
substrate 102 via the adhesion layer 132. In the first embodiment,
the upper surface of the reflective layer 142 serves as the
reflective surface. The reflective surface has a plurality of
concavo-convex structure units. The concavo-convex structure unit
consists of a depression or a protrusion. The reflective layer 142
is provided along the surface of the concavo-convex structure
portion 141.
(Substrate and Sealing Substrate)
[0045] Examples of substrates that may be employed for the
substrate 101 and the sealing substrate 102 may include substrates
that may be generally used as an organic EL light-emitting element
substrate, such as a glass substrate, quartz substrate, and plastic
substrate. The material forming the substrate 101 may be the same
as or different from that forming the sealing substrate 102. The
thickness of each of the substrate and sealing substrate may be
0.01 to 5 mm.
(Light-Emitting Element)
[0046] In the present embodiment, the light-emitting element 120
includes a first transparent electrode layer 111, a light-emitting
layer 121, and a second transparent electrode layer 112, in this
order from the light-emitting side.
[0047] The light-emitting layer 121 is not particularly limited,
and a known light-emitting layer may be appropriately selected
therefor. For adaptation to its use as a light source, the
light-emitting layer may be a single type of layer or a combination
of a plurality of types of layers which is capable of emitting
light that includes the below-described specific peak
wavelength.
[0048] The first transparent electrode layer 111 is positioned
closer to the light-emitting surface than the light-emitting layer
121, and the second transparent electrode layer 112 is positioned
closer to the reflective layer than the light-emitting layer 121.
The materials forming the respective transparent electrode layers
111 and 112 are not limited to particular materials, and may be
appropriately selected from among known materials that are used for
an organic EL light-emitting element electrode. Either the first
transparent electrode layer 111 or the second transparent electrode
layer 112 is made to serve as the anode, while the other is made to
serve as the cathode. In addition to the light-emitting layer,
other layers may be provided between the electrodes, such as a hole
injection layer, a hole transport layer, an electron transport
layer, an electron injection layer, and a gas barrier layer.
[0049] Examples of the material for the first transparent electrode
layer 111 and the second transparent electrode layer 112 may
include a thin metal layer, ITO, IZO, and SnO.sub.2.
[0050] Specific examples of the layer configuration of the
light-emitting layer may include: a configuration of anode/hole
transport layer/light-emitting layer/cathode; a configuration of
anode/hole transport layer/light-emitting layer/electron injection
layer/cathode; a configuration of anode/hole injection
layer/light-emitting layer/cathode; a configuration of anode/hole
injection layer/hole transport layer/light-emitting layer/electron
transport layer/electron injection layer /cathode; a configuration
of anode/hole transport layer /light-emitting layer/electron
injection layer/equipotential surface forming layer/hole transport
layer /light-emitting layer/electron injection layer/cathode; and a
configuration of anode/hole transport layer/light-emitting
layer/electron injection layer/charge generation layer/hole
transport layer/light-emitting layer/electron injection
layer/cathode. The light-emitting element in the organic EL light
source device of the present invention may have one or more
light-emitting layers between the anode and the cathode. Further,
the light-emitting layer may have a stacked body of layers having a
plurality of different emission colors, or a mixed layer that is a
certain pigment layer which is doped with a different pigment. The
materials for these layers are not particularly limited. Examples
of the material forming the light-emitting layer may include
polyparaphenylenevinylene-based materials, polyfluorene-based
materials, and polyvinylcarbazole-based materials. Examples of the
material forming the hole injection layer and the hole transport
layer may include phthalocyanine-based materials, arylamine-based
materials, and polythiophene-based materials. Examples of the
material forming the electron injection layer and the electron
transport layer may include aluminum complexes and lithium
fluoride. Examples of the equipotential surface forming layer and
the charge generation layer may include a transparent electrode
formed from ITO, IZO, SnO.sub.2 and the like, and a thin metal
layer of Ag, Al and the like.
[0051] The first transparent electrode layer 111, the
light-emitting layer 121, the second transparent electrode layer
112, and other optional layers forming the light-emitting element
120 may be provided on the substrate 101 by successively stacking
these layers. The thickness of each layer may be 10 to 1,000
nm.
(Sealing Layer)
[0052] Examples of materials that may be used to form the sealing
layer 131 may include resins that have a function of causing
adhesion of the second transparent electrode layer 112 and the
sealing substrate 102, and that can prevent degradation of the
light-emitting element 120 due to contact with moisture, oxygen and
the like in the air when the device is used. The material forming
the sealing layer 131 does not have to be a solid. For example, an
inactive liquid such as a fluorohydrocarbon, silicon oil and the
like, or a liquid crystal material of nematic liquid crystals,
smectic liquid crystals and the like may be used.
[0053] Examples of materials that may be used for forming the
sealing layer 131 may include an energy beam curable resin such as
an acrylate resin, a methacrylate resin and the like,
sticky-bonding function resins and adhesive-bonding function resins
of an acrylic type, an olefinic type and the like, and a
thermofusion type adhesive-bonding function resin that melts when
heated and hardens when cooled. The "sticky-bonding function resin"
herein may be a material that has a shear storage elastic modulus
at a temperature of 23.degree. C. of 0.1 to 10 MPa, and the
"adhesive-bonding function resin" may be a material having a higher
shear storage elastic modulus than that of the previous resin.
[0054] Examples of thermofusion type adhesive-bonding function
resins for use that melt when heated and harden when cooled may
include resins having a glass transition temperature (Tg) of
usually -50 to 200.degree. C., preferably -10 to 100.degree. C.,
more preferably 20 to 90.degree. C., and particularly preferably 50
to 80.degree. C. By setting the glass transition temperature in the
aforementioned preferred range, a light source device having
sufficient heat resistance can be obtained, and adhesion can be
effected without damaging the light-emitting layer constituting the
light source device.
[0055] As the sticky-bonding function resin or adhesive-bonding
function resin, a conjugated diene polymer cyclized product
obtained by cyclizing a conjugated diene polymer may be used, in
which the decrease ratio in unsaturated bonds present in the
conjugated diene polymer cyclized product based on the unsaturated
bonds in the conjugated diene polymer (unsaturated bond decrease
ratio) is 30% or more. Further, as the sticky-bonding function
resin or adhesive-bonding function resin, a composition containing
a conjugated diene polymer cyclized product and an alicyclic olefin
resin may also be used.
[0056] The conjugated diene polymer cyclized product may be
obtained by cyclizing a conjugated diene polymer in the presence of
an acid catalyst. As the conjugated diene polymer, a homopolymer
and copolymer of conjugated diene monomers, as well as a copolymer
of a conjugated diene monomer and other monomers may be used.
[0057] The conjugated diene monomer is not particularly limited.
Specific examples thereof may include 1,3-butadiene, isoprene,
2,3-dimethyl-1,3-butadiene, 2-phenyl- 1,3-butadiene,
1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene,
4,5-diethyl-1,3-octadiene, and 3-butyl-1,3-octadiene. One species
of these monomers may be solely used, or a combination of two or
more thereof may also be used in combination.
[0058] Specific examples of the conjugated diene polymer may
include a homopolymer or copolymer of a conjugated diene such as
natural rubber, polyisoprene, and a butadiene-isoprene copolymer;
and a copolymer of a conjugated diene with another monomer, such as
a styrene-butadiene copolymer, a styrene-isoprene copolymer, an
isoprene-isobutylene copolymer, an ethylene-propylene-diene-based
copolymer rubber, and an aromatic vinyl-conjugated diene block
copolymer such as a styrene-isoprene block copolymer. Of these,
natural rubber, polyisoprene, and a styrene-isoprene block
copolymer are preferred, and polyisoprene and a styrene-isoprene
block copolymer are more preferred.
[0059] Further, as the conjugated diene polymer cyclized product,
it is preferable to use a modified conjugated diene polymer
cyclized product that has been modified with a polar group. The
modified conjugated diene polymer cyclized product has an effect of
causing sticky-bonding ability or adhesive-bonding ability to the
adherend. If fine particles are included in the sticky-bonding
function resin or adhesive-bonding function resin, the modified
conjugated diene polymer cyclized product has an effect of
improving the dispersibility of those fine particles. The
sticky-bonding function resin or adhesive-bonding function resin
may contain a single species of polar group-containing modified
conjugated diene polymer cyclized product. Alternatively, the
sticky-bonding function resin or adhesive-bonding function resin
may contain a plurality of modified conjugated diene polymer
cyclized products respectively containing a plurality of different
types of polar group. In addition, a conjugated diene polymer
cyclized product having two or more types of functional group may
also be used.
[0060] The polar group is not particularly limited. Examples
thereof may include an acid anhydride group, a carboxyl group, a
hydroxyl group, a thiol group, an ester group, an epoxy group, an
amino group, an amido group, a cyano group, a silyl group, and a
halogen.
[0061] Examples of the acid anhydride group or carboxyl group may
include groups having a structure formed by adding a vinyl
carboxylic acid compound, such as maleic anhydride, itaconic
anhydride, aconitic anhydride, norbornene dicarboxylic anhydride,
acrylic acid, methacrylic acid, and maleic acid, to a conjugated
diene polymer cyclized product. Among these, from the perspectives
of reactivity and cost efficiency, a group having a structure
formed by adding maleic anhydride to a conjugated diene polymer
cyclized product is preferred.
[0062] The amido group may be introduced by a method in which an
unsaturated compound containing an amido group is grafted onto a
conjugated diene polymer cyclized product; or a method in which a
functional group is introduced using an unsaturated compound
containing the functional group and then this introduced functional
group is reacted with a compound having an amido group. Examples of
the unsaturated compound containing an amido group may include
acrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, and
N-benzylacrylamide.
[0063] Examples of the hydroxyl group may include groups having a
structure formed by, to a conjugated diene polymer cyclized
product, adding hydroxyalkyl esters of an unsaturated acid such as
2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate,
unsaturated amides having a hydroxyl group such as N-methylol
(meth)acrylamide and N-(2-hydroxyethyl) (meth) acrylamide,
polyalkylene glycol monoesters of an unsaturated acid such as
polyethylene glycol mono(meth)acrylate, polypropylene glycol
mono(meth)acrylate, and poly(ethylene glycol-propylene glycol)
mono(meth)acrylate, and a polyhydric alcohol monoester of an
unsaturated acid such as glycerol mono(meth)acrylate. Among these,
hydroxyalkyl esters of an unsaturated acid are preferred, and in
particular, groups having a structure formed by adding
2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate to a
conjugated diene polymer cyclized product are preferred.
[0064] Examples of the vinyl compound containing other polar groups
may include methyl (meth)acrylate, ethyl (meth)acrylate, butyl
(meth)acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth)
acrylate, dimethylaminopropyl (meth) acrylate, (meth) acrylamide,
and (meth) acrylonitrile.
[0065] Although the content of polar groups in the modified
conjugated diene polymer cyclized product, particularly in the
polar group-containing conjugated diene polymer cyclized product,
is not particularly limited, usually the content is in the range of
0.1 to 15 mol. %, preferably in the range of 0.5 to 10 mol. %, and
more preferably in the range of 1 to 7 mol. %. If this content is
too low or too high, the oxygen absorption function tends to
deteriorate. The polar group content is based on a molecular weight
equivalent of the polar groups bound to a molecule of the modified
conjugated diene polymer cyclized product of 1 mole.
[0066] Examples of the method for producing the modified conjugated
diene polymer cyclized product may include: (1) a method of adding
a polar group-containing vinyl compound to a conjugated diene
polymer cyclized product obtained by the aforementioned method; (2)
a method of cyclizing a conjugated diene polymer containing a polar
group by the aforementioned method; (3) a method of adding a polar
group-containing vinyl compound to a conjugated diene polymer that
does not contain a polar group and then cyclizing the compound; and
(4) a method of further adding a polar group-containing vinyl
compound to a product obtained by the aforementioned method (2) or
(3). Among these methods, from the perspective of facilitating the
adjustment of the unsaturated bond decrease ratio, the
aforementioned method (1) is preferred.
[0067] The polar group-containing vinyl compound is not
particularly limited, as long as it can introduce a polar group
onto a conjugated diene polymer cyclized product. Preferred
examples thereof may include vinyl compounds having a polar group
such as an acid anhydride group, a carboxyl group, a hydroxyl
group, a thiol group, an ester group, an epoxy group, an amino
group, an amido group, a cyano group, a silyl group, and a
halogen.
[0068] Examples of the vinyl compound having an acid anhydride
group or a carboxyl group may include maleic anhydride, itaconic
anhydride, aconitic anhydride, norbornene dicarboxylic anhydride,
acrylic acid, methacrylic acid, and maleic acid. Among these, from
the perspectives of reactivity and cost efficiency, it is preferred
to use maleic anhydride. Preferred examples of the hydroxyl
group-containing vinyl compound may include hydroxyalkyl esters of
an unsaturated acid, and in particular, 2-hydroxyethyl acrylate and
2-hydroxyethyl methacrylate.
[0069] Although the method for adding the polar group-containing
vinyl compound to the conjugated diene polymer cyclized product to
introduce the polar group derived from this polar group-containing
vinyl compound is not particularly limited, this can be carried out
based on a generally known method such as an "ene-addition
reaction" or a "graft polymerization reaction". In this addition
reaction, the conjugated diene polymer cyclized product and the
polar group-containing vinyl compound are brought into contact with
each other, optionally in the presence of a radical generator.
Examples of the radical generator may include peroxides such as
di-tert-butyl peroxide, dicumyl peroxide, and benzoyl peroxide, and
azonitriles such as azobisisobutyronitrile.
[0070] Other than those with 100% cyclization rate, the conjugated
diene polymer cyclized product has at least two kinds of
unsaturated bonds, i.e., straight-chain unsaturated bonds
originally in the conjugated diene and cyclic unsaturated bonds of
the cyclized moiety. It is thought that, in the conjugated diene
polymer cyclized product, the cyclic unsaturated bond moiety
greatly contributes to oxygen absorption, whereas the
straight-chain unsaturated bond moiety makes almost no contribution
to oxygen absorption. Consequently, a conjugated diene polymer
cyclized product that has an unsaturated bond decrease ratio in the
conjugated diene polymer cyclized product based on the unsaturated
bonds in the conjugated diene polymer (unsaturated bond decrease
ratio) of 30% or more is preferred as the material for the oxygen
absorbing member in the light-emitting element of the present
invention. It is preferred that the unsaturated bond decrease ratio
of the conjugated diene polymer cyclized product is 40 to 75%, and
more preferably 55 to 70%. If the unsaturated bond decrease ratio
is too low, the oxygen absorption properties tend to deteriorate.
Setting the unsaturated bond decrease ratio of the conjugated diene
polymer cyclized product to no more than the upper limit of the
aforementioned preferred range can prevent the conjugated diene
polymer cyclized product from becoming brittle, facilitate
production, suppress gellation from progressing during production,
and improve its transparency. Consequently, the device utilizing
the conjugated diene polymer cyclized product can be used in a wide
range of applications. Further, since sticky-bonding properties or
adhesive-bonding properties are exhibited if the unsaturated bond
decrease ratio exceeds 50%, this characteristic can also be
utilized.
[0071] The unsaturated bond decrease ratio is an index that
represents the level of reduction in unsaturated bonds due to the
cyclization reaction in the conjugated diene monomer unit moiety in
the conjugated diene polymer. This unsaturated bond decrease ratio
is a value obtainable by the following procedure. The ratio of the
peak area of the protons directly bound to a double bond relative
to the peak area of all protons in the conjugated diene monomer
unit moiety in the conjugated diene polymer is measured by proton
NMR (.sup.1H-NMR) analysis, both before and after the cyclization
reaction. On the basis of the measurement results, the decrease
ratio is calculated.
[0072] Regarding the conjugated diene monomer unit moiety in the
conjugated diene polymer, suppose that the peak area of all protons
before the cyclization reaction is SBT, the peak area of the
protons directly bound to a double bond before the cyclization
reaction is SBU, the peak area of all protons after the cyclization
reaction is SAT, and the peak area of the protons directly bound to
a double bond after the cyclization reaction is SAU. Then, the peak
area ratio (SB) of the protons directly bound to a double bond
before the cyclization reaction is represented as SB=SBU/SBT, and
the peak area ratio (SA) of the protons directly bound to a double
bond after the cyclization reaction is represented as SA=SAU/SAT.
Therefore, the unsaturated bond decrease ratio can be determined
by,
[0073] Unsaturated bond decrease ratio (%)=100.times.(SB-SA)/SB
[0074] The oxygen absorption amount of the conjugated diene polymer
cyclized product used in the present invention is 5 ml/g or more,
preferably 10 ml/g or more, and more preferably 50 ml/g. The oxygen
absorption amount is the amount of oxygen that is absorbed by 1 g
of conjugated diene polymer cyclized product when the conjugated
diene polymer cyclized product as powders or a thin layer has
become saturated by sufficient oxygen absorption at 23.degree. C.
If the oxygen absorption amount is low, a large quantity of
conjugated diene polymer cyclized product is necessary in order to
stably absorb oxygen for a long period of time. The oxygen
absorption amount is mainly correlated with the decrease ratio of
the unsaturated bond present in the conjugated diene polymer
cyclized product.
[0075] In the present invention, the conjugated diene polymer
cyclized product for use has a rate of oxygen absorption from its
surface of 1.0 ml/m.sup.2 per day or more, preferably 5.0
ml/m.sup.2 per day or more, and more preferably 10 ml ml/m.sup.2
per day or more. Even when the conjugated diene polymer cyclized
product has a large oxygen absorption ability, if the rate of
oxygen absorption is too slow, oxygen that has infiltrated from
outside cannot be sufficiently absorbed, and can permeate
therethrough. Further, when used as a sealing layer of the
light-emitting element, oxygen that is for some reason present in
the sealed space or that has infiltrated therein must be quickly
removed by absorption with the conjugated diene polymer cyclized
product layer. Also from such a perspective, it is preferred to
have the aforementioned rate of oxygen absorption.
[0076] The content of the conjugated diene polymer cyclized product
in the sticky-bonding function resin or adhesive-bonding function
resin is usually 5 to 90 wt. %, and is preferably 15 to 70 wt. %.
The conjugated diene polymer cyclized product content below this
lower limit may cause a problem of a deterioration in the oxygen
absorption ability and adhesive force at ordinary temperature
(23.degree. C.) Further, the content exceeding the aforementioned
upper limit may cause a problem of a deterioration in mechanical
strength.
[0077] The aforementioned alicyclic olefinic resin is an amorphous
resin having an alicyclic structure, such as a cycloalkane
structure or a cycloalkene structure, in its main chain and/or on a
side chain. From the perspective of mechanical strength and heat
resistance, a polymer containing an alicyclic structure in its main
chain is preferred. Examples of the alicyclic structure may include
a monocycle structure or a polycycle structure (fused polycycle,
crosslinked ring etc.). Among alicyclic structures, a cycloalkane
structure is preferred. Although the number of carbon atoms forming
one unit of the alicyclic structure is not particularly limited, if
the number is usually in the range of 4 to 30, preferably 5 to 20,
and more preferably 5 to 15, properties such as mechanical
strength, heat resistance, and molding properties are highly
balanced, and thus the number in such a range is preferred.
Specific examples of the aforementioned alicyclic olefin resin may
include (1) a norbornene polymer, (2) a polymer of a monocyclic
olefin, (3) a polymer of a cyclic conjugated diene, (4) a vinyl
alicyclic hydrocarbon polymer, and mixtures thereof. Among these,
from the perspectives of optical properties, heat resistance, and
mechanical strength, a norbornene polymer and a vinyl alicyclic
hydrocarbon polymer are preferred. Further, if an alicyclic olefin
resin having a polar group is used as the alicyclic olefin resin,
affinity with inorganic products can be improved without harming
light transmittance.
[0078] Although the method for forming the sealing layer 131 is not
particularly limited, the sealing layer 131 may be formed by
arranging a layer of a sticky-bonding function resin or
adhesive-bonding function resin such as those described above on
the sealing substrate 102 and/or the second transparent electrode
layer 112, attaching the sealing substrate 102 and second
transparent electrode layer 112 together via the sticky-bonding
function resin layer or adhesive-bonding function resin layer, and
optionally heating the layers to fuse them together. The thickness
of the sealing layer may be 1 to 1,000 .mu.m.
[0079] Usually, such a sticky-bonding function resin or
adhesive-bonding function resin is not capable by itself of
blocking the moisture and oxygen in the air, and the blocking of
the exterior air may be effected by the substrate 101 and the
sealing substrate 102. However, by using a material capable of
absorbing oxygen and moisture as the material of the sealing layer
131 that is sealed between the substrate 101 and sealing substrate
102, deterioration of the light-emitting element 120 can be more
effectively prevented, so that a light source device having a
longer life can be produced.
(Reflective Surface)
[0080] The light source device of the present invention has a
specific relationship between the shape of the reflective surface
of the reflective layer and the refractive index of a structural
layer X that is provided between the second transparent electrode
layer and the reflective surface and is in contact with the
reflective surface. Specifically, a refractive index n of the
structural layer X, an inclination angle .theta..times.1 of a
concavo-convex structure unit, and a mean inclination angle
.theta..times.2 of the concavo-convex structure unit of the
reflective surface satisfy the following expressions (1) and
(2).
.theta..times.1.ltoreq.sin.sup.-1(1/n) (1)
{90-sin.sup.-1(1/n)}/3.ltoreq..theta..times.2sin.sup.-1(1/n)tm
(2)
[0081] The element in the first embodiment corresponding to the
structural layer X is the adhesion layer 132. Further, the surface
of the reflective layer 142 in contact with the adhesion layer 132
serves as the reflective surface of the reflective layer. The
reflective portion composite substrate 140 serves as a member that
defines the concavo-convex structure of the reflective surface.
Specifically, by providing the reflective layer 142 along the
concavo-convex structure of the concavo-convex structure portion
141 of the reflective portion composite substrate 140, the
concavo-convex structure of the reflective surface of the
reflective layer 142 has the same shape as the concavo-convex
structure of the concavo-convex structure portion 141. Therefore, a
desired reflective surface shape can be obtained by forming the
reflective portion composite substrate 140 so that the shape of the
surface of the concavo-convex structure portion 141 satisfies the
relationship of the aforementioned formulae (1) and (2), and
forming the reflective layer 142 having a uniform thickness on the
thus-formed reflective portion composite substrate 140. However,
the reflective layer in the present invention is not limited to
those having a uniform thickness. For example, the reflective layer
may also be formed of a concavo-convex metal layer on a flat
substrate.
[0082] An example of the detailed structure of the concavo-convex
structure portion 141 according to the first embodiment is
illustrated in FIG. 2. FIG. 2 is an enlarged perspective view
schematically illustrating the concavo-convex structure portion 141
of the reflective portion composite substrate 140 illustrated in
FIG. 1. In the first embodiment, the shape of the reflective
surface of the reflective layer 142 is the same shape as the
surface shape of the concavo-convex structure portion 141.
[0083] The concavo-convex structure of the reflective portion
composite substrate 140 is a structure in which a plurality of
concavo-convex structure units 14Z, which are depressions with a
quadrangular pyramid shape, are aligned. In this example, the
concavo-convex structure units 14Z are continuously aligned in two
in-plane directions (the X axis direction and the Y axis direction
in FIG. 2) that bisect each other.
[0084] Each of the concavo-convex structure units 14Z has four
oblique faces 14A to 14D and an apex 14T. The angle between each of
the four oblique faces 14A to 14D and the horizontal plane is the
same. The bottom face of the quadrangular pyramid shape of the
concavo-convex structure units 14Z is in a square shape. Bottom
edges 14E of the quadrangular pyramid shape of the concavo-convex
structure units 14Z are in contact with the bottom edges of other
concavo-convex structure units 14Z. Consequently, the
concavo-convex structure units 14Z are continuously arranged
without any gaps on the concavo-convex structure. Although the
concavo-convex structure units 14Z are continuously arranged
without any gaps in the present embodiment, the concavo-convex
structure units 14Z may also be arranged so that there is a gap to
an adjacent unit. In this case, it is preferred that the separated
portion (gap) is a flat plane.
[0085] FIG. 3 is a partial cross-sectional view illustrating the
concavo-convex structure unit 14Z of the reflective portion
composite substrate 140 along a plane that passes through the line
2a parallel to the bottom edge 14E and that is parallel to the Z
axis direction. An angle .theta.14 formed between the oblique faces
14B and 14D and the horizontal plane is an inclination angle
.theta..times.1 of the concavo-convex structure unit 14Z. Further,
since the shape of the concavo-convex structure units 14Z is the
same across the overall surface having the concavo-convex structure
of the concavo-convex structure portion 141, the inclination angle
.theta.14 of the concavo-convex structure unit 14Z is also the mean
inclination angle .theta..times.2 of the concavo-convex structure
of the reflective surface.
[0086] In the present invention, if the concavo-convex structure
has a plurality of differently shaped concavo-convex structure
units, the maximum angle among the plurality of concavo-convex
structures is taken as the inclination angle .theta..times.1 of
those units. Further, when there is a flat portion between the
concavo-convex structure units, the flat portion is excluded when
determining the mean inclination angle.
[0087] In the present invention, if the concavo-convex structure
has a plurality of types of slope or has curved surfaces and is
more complex than the aforementioned example, the mean inclination
angle .theta..times.2 is defined as follows. That is, the
reflective surface is divided into n-number of tiny surface areas
sufficiently smaller than the concavo-convex structure unit. Each
of these tiny surface areas is defined as .DELTA.Si, the value of
the angle between this .DELTA.Si and the substrate flat surface is
defined as .theta.i, and the mean inclination angle is then defined
by the following formula (5).
Mean inclination angle = i = 0 n ( .DELTA.Si .times. .theta. i ) /
i = 0 n .DELTA.Si ##EQU00001##
[0088] In the formula (5), .SIGMA..DELTA.Si represents the total
surface area of the reflective layer. In the light source device of
the present invention, when the thus-defined mean inclination angle
of the reflective layer satisfies the aforementioned specific
requirement, a high light extraction efficiency can be
realized.
[0089] The reflective portion composite substrate 140 may be molded
so that the concavo-convex structure portion 141 and portions below
that are integrally molded with a common material. Alternatively,
the concavo-convex structure portion 141 and the portions below
that may be molded with different materials.
[0090] When the concavo-convex structure portion 141 and the
portions below that are integrally molded with a common material,
examples of the material therefor may include the same material as
that forming the substrate 101 and sealing substrate 102. From the
perspective of facilitating manufacture of the concavo-convex
structure portion 141, a plastic substrate is preferred. More
specifically, a material formed of the aforementioned alicyclic
olefin resin and the like may be used.
[0091] When the concavo-convex structure portion 141 and the
portions below that are molded with different materials, the same
material as described above may be used for the portions below the
concavo-convex structure portion 141. On the other hand, as the
material for forming the concavo-convex structure portion 141, from
the perspective of facilitating molding process, a resin that can
be cured with an energy beam such as UV-rays is preferred.
Specifically, a material such as a (meth)acrylate-based energy
beam-curable resin may be used. The concavo-convex structure
portion 141 having a desired concavo-convex structure may be easily
formed by coating with such a resin the surface of a specific
substrate that forms a part of the aforementioned portions below
the concavo-convex structure portion 141, pressing a mold having a
desired shape against the coated resin, and curing the resin by
irradiation of the resin with an energy beam from the sealing
substrate 102 side.
[0092] The thickness of the reflective portion composite substrate
140 may be 25 to 500 .mu.m. The height of the
depressions/protrusions of the concavo-convex structure may be 0.3
to 100 .mu.m. The width of the depressions/protrusions of the
concavo-convex structure may be 0.6 to 200 .mu.m.
[0093] The reflective layer 142 may be provided by, for example,
forming one or a plurality of layers of a metal on a member
defining the concavo-convex structure, such as the reflective
portion composite substrate. Examples of metals that may be used
for this metal layer may include aluminum and alloys thereof,
silver and alloys thereof and the like. Silver is particularly
preferred because of its high reflectance.
[0094] It is preferred that the reflective layer is a stacked body
formed of a first metal layer including a first metal and a second
metal layer including a second metal which is different from the
first metal. Specifically explaining, if silver, which has a high
reflectance, is provided at a thickness that can obtain a
sufficient reflectance, production costs increase. Then the
reflective layer may be formed by employing silver and aluminum,
which is cheaper but has poorer reflectance than silver, for the
first and second metals respectively, and stacking an aluminum
layer and a silver layer. More specifically, the reflective layer
may be formed by providing a silver layer on an upper side of an
aluminum layer and using this silver layer as the reflective
surface. Preferably, the layer of silver is provided in direct
contact with the top of the aluminum layer.
[0095] Particularly, when the reflective layer 142 is made of
metal, the role of blocking oxygen and moisture in the air from
infiltrating into the light-emitting element can also be achieved
by the reflective layer 142 in addition to the sealing substrate
102.
(Adhesion Layer)
[0096] In the first embodiment, although the same materials as
those exemplified for the sealing layer 131 (various sticky-bonding
function resins or adhesive-bonding function resins) may be used
for the material forming the adhesion layer 132 for causing
adhesion of the sealing substrate 102 and the reflective layer 142,
the material for the adhesion layer 132 is not limited to those
examples. For example, various known adhesives for effecting
adhesion of optical members and the like may be used. Specifically,
Aron Alpha (registered trademark) manufactured by Toagosei Co.,
Ltd., and the like may be used. If the adhesion layer serves as the
structural layer X in the present invention, it is preferred that
the refractive index of the adhesion layer is in the
below-described preferred range as the refractive index n of the
structural layer X.
[0097] The method for forming the adhesion layer 132 is not
particularly limited. The adhesion layer 132 may be formed by
coating a composition for forming the adhesion layer on the surface
of the sealing substrate 102 and/or reflective layer 142, attaching
the sealing substrate 102 and reflective layer 142 together via the
coated layer of this composition, and optionally photocuring,
heating, and drying it. The thickness of the reflective layer may
be 1 to 1,000 .mu.m. It is preferred to provide the adhesion layer
132 on the reflective surface so that the concavo-convex structure
of the reflective surface is filled therewith and the surface
becomes flat.
(Diffusion Layer)
[0098] The organic EL light source device of the present invention
may further include optional layers in addition to the essential
components that are the first transparent electrode layer,
light-emitting layer, second transparent electrode layer,
structural layer X, and reflective layer. For example, the organic
EL light source device may further include a light diffusion layer
provided on the light-emitting surface side of the reflective
layer.
[0099] This diffusion layer may be provided at an arbitrary
position on the light-emitting surface side of the reflective
layer. The diffusion layer may be provided as a separate layer from
the aforementioned layers that are essential components.
Alternatively, the diffusion layer may be provided as a layer that
also serves as a layer that is an essential component, such as the
structural layer X. The diffusion layer may be any of the layers
described above, for example, the substrate, sealing substrate,
sealing layer, sticky-bonding layer, and adhesion layer, to which a
function as a diffusion layer is imparted. Specifically, the
diffusion layer is a layer positioned below but close to the
light-emitting element, and may be formed of a material to which a
diffusing agent can be easily added, such as a resin. For example,
in the first embodiment, it is preferred to impart a function as a
diffusion layer to the sealing layer 131, thereby using this layer
as the diffusion layer. Although the material for the diffusion
layer is not particularly limited, it is preferred that the
material is a resin that forms, e.g., the sealing layer to which a
diffusing agent is added. A structure in which a material having a
refractive index higher than glass and containing a diffusing agent
added thereto is used as the sealing layer is particularly
preferred because light extraction efficiency can be improved while
also suppressing the metallic luster of the reflective layer. The
haze of the diffusion layer may be 25 to 95%, and more preferably
70 to 90%. By setting the haze range to no less than the
aforementioned lower limit, effects of the diffusion layer can be
obtained. Further, by setting the haze range to no more than the
aforementioned upper limit, a thin layer thickness can be obtained.
By incorporating such a diffusion layer into the light source
device, light interference in the device can be further decreased
and a higher extraction efficiency can be realized.
(Light Path)
[0100] In the organic EL light source device of the first
embodiment, the light-emitting layer 121 emits light by application
of a voltage to the first transparent electrode layer 111 and the
second transparent electrode layer 112. The produced light emits
from the light-emitting layer 121 in arbitrary directions.
[0101] Part of the light that is emitted upwards passes through the
first transparent electrode layer 111, through the substrate 101,
and is emitted from a light-emitting surface 100A. However, the
light that is reflected at the interfaces proceeds in a downward
direction. Particularly, light that is incident on an interface at
a greater angle than the critical angle of the interface is totally
reflected, and all of such light proceeds in a downward
direction.
[0102] Much of the light that is emitted from the light-emitting
layer in a downward direction passes through the second transparent
electrode layer 112, then passes through the sealing layer 131, the
sealing substrate 102, and the adhesion layer 132, and reaches the
reflective surface of the reflective layer 142.
[0103] Generally, if reflection at the layer interfaces in the
device is repeated many times, the energy of the light is lost due
to interference and absorption. Therefore, from the perspective of
increasing the light extraction efficiency, it is preferred that
the light that has been emitted in a downward direction is
reflected in a direction which does not repeat total
reflection.
[0104] Here, a case in which light that has reached the structural
later X (in the first embodiment, the adhesion layer 132) and been
reflected by the reflective surface is emitted from light-emitting
surface of the device will be considered. In this case, even if
another layer is present between the light-emitting surface of the
device and the structural layer X, the reflected light is in the
end emitted from the device towards the exterior, which is a layer
of air. Consequently, among the angle range of the light rays that
are reflected by the reflective surface and then directed toward
the light-emitting surface side of the device at various angles,
the angle range in which the light can go out of the light-emitting
surface of the device while keeping that angle (i.e., without light
path direction change other than change by refraction (diffusion
due to a diffusing agent, refraction and reflection at a surface
that is not parallel to the light-emitting surface of the device
etc.)) depends, in the end, on the relative refractive index of the
structural layer X which is the layer in contact with the
reflective surface, and the air layer. This relative refractive
index can simply be approximated by the refractive index n of the
structural layer X.
[0105] More specifically, when light proceeding downwards through
the structural layer X in a direction in which the angle with
respect to the Z axis direction is greater than the critical angle
at an interface between the structural layer X and the air layer
(hereinafter simply referred to as "critical angle of structural
layer X") is reflected at the reflective surface and proceeds in an
upward direction, it is desired that as much of the reflected light
as possible proceed in a direction in which the angle with respect
to the Z axis direction is smaller than the critical angle of
structural layer X. Here, if the reflective surface satisfies the
aforementioned expressions (1) and (2), the ratio of reflection in
such a desired manner increases, and thereby the extraction
efficiency can be improved.
[0106] In the present invention, it is more preferred that the mean
inclination angle .theta..times.2 satisfy the following expression
(3), and even more preferred that it satisfy the following
expression (4).
{90-sin.sup.-1(1/n)}/2.ltoreq..theta..times.2sin.sup.-1(1/n)
(3)
({90+sin.sup.-1(1/n)}/4)-5.ltoreq..nu..times.2({90+sin.sup.-1(1/n)}/4)+5
(4)
[0107] When the reflective surface has a shape in which pyramids
are aligned without any gap between them, it is particularly
preferred that the reflective surface satisfy the aforementioned
expression (3), because even with two consecutive reflections as
illustrated by the arrow in FIG. 10, when the light proceeding
downwards through the structural layer X at an angle greater than
the critical angle of the structural layer X is reflected by the
reflective surface and proceeds upwards, most of the light proceeds
in a direction in which the angle with respect to the Z axis
direction is smaller than the critical angle of the structural
layer X.
[0108] Further, when the aforementioned expression (4) is
satisfied, the light in the direction in which the angle with
respect to the Z axis direction is an angle within a range from the
critical angle of the structural layer X to 90.degree. (for
example, when n=1.53 and the critical angle is 40.8.degree., light
in the direction in which the angle with respect to the Z axis
direction is 65.4.degree., which is 40.8 to) 90.degree. can be
reflected in a direction that is close to the Z axis direction.
Consequently, even more preferred reflection can be achieved.
[0109] The ranges of the aforementioned expressions (2) to (4) when
the refraction index n is a variety of representative refractive
index values are as follows.
[0110] When n=1.5, expression (2):
16.1.ltoreq..theta..times.2.ltoreq.41.8, expression (3):
24.1.ltoreq..theta..times.2.ltoreq.41.8, expression (4):
28.0.ltoreq..theta..times.2.ltoreq.38.0.
[0111] When n=1.6, expression (2):
17.1.ltoreq..theta..times.2.ltoreq.38.7, expression (3):
25.7.ltoreq..theta..times.2.ltoreq.38.7, expression (4):
27.2.ltoreq..theta..times.2.ltoreq.37.2.
[0112] When n=1.8, expression (2):
18.8.ltoreq..theta..times.2.ltoreq.33.7, expression (3):
28.1.ltoreq..theta..times.2.ltoreq.33.7, expression (4):
25.9.ltoreq..theta..times.2.ltoreq.35.9.
[0113] When n=1.9, expression (2):
19.4.ltoreq..theta..times.2.ltoreq.31.8, expression (3):
29.1.ltoreq..theta..times.2.ltoreq.31.8, expression (4):
25.4.ltoreq..theta..times.2.ltoreq.35.4.
[0114] It is preferred that the value of the refractive index n of
the structural layer X is equal to or greater than the refractive
index of the substrate and the sealing substrate. If the substrate
and sealing substrate are formed of an ordinary material such as a
glass or a film, the lower limit for the refractive index n of the
structural layer X is preferably 1.5 or more, and more preferably
1.6 or more. On the other hand, since the refractive index of the
structural layer X does not have to be equal to or greater than the
refractive index of the light-emitting element, the upper limit for
the refractive index of the structural layer X is preferably 1.9 or
less. In the present invention, the refractive index may be set
based on light having a wavelength of 550 nm.
Second Embodiment
[0115] FIG. 4 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a second embodiment of the present invention.
In FIG. 4, a device 400 differs from the first embodiment in that
it includes a transparent concavo-convex layer 440 having a
concavo-convex structure portion 441 on its lower surface, and a
reflective layer 442 provided on the lower surface of the
concavo-convex structure portion 441. The transparent
concavo-convex layer 440 is provided on a lower side of the sealing
substrate 102 via an adhesion layer 432. In the second embodiment
illustrated in FIG. 4, the transparent concavo-convex layer 440 is
the member that defines the concavo-convex structure of the
reflective surface of the reflective layer. Specifically, the
reflective layer 442 is provided along the concavo-convex structure
portion 441 of the transparent concavo-convex layer 440, whereby
the reflective surface of the reflective layer 442 is of a shape
that has the specific concavo-convex structure of the present
invention.
[0116] In the second embodiment, it is not the adhesion layer 432
but the transparent concavo-convex layer 440 that serves as the
structural layer X. Further, the surface of the reflective layer
442 that is in contact with the concavo-convex structure portion
441 of the transparent concavo-convex layer 440 serves as the
reflective surface of the reflective layer. With such a
configuration, the requirements of the present invention can also
be satisfied, and the desired effect that are a high light
extraction efficiency and other effects can be obtained.
[0117] Similar to the reflective portion composite substrate 140,
the transparent concavo-convex layer 440 may be molded so that the
concavo-convex structure portion 441 and the portions above that
are integrally molded with a common material. Alternatively, the
concavo-convex structure portion 441 and the portions above that
may be molded with different materials. The materials and the
production method for the transparent concavo-convex layer 440 may
be the same as those described above for the reflective portion
composite substrate 140. The thickness of the transparent
concavo-convex layer 440 may be 1 to 500 .mu.m. The height of the
depressions/protrusions of the concavo-convex structure may be 0.3
to 100 .mu.m. The width of the depressions/protrusions of the
concavo-convex structure may be 0.6 to 200 .mu.m.
Third Embodiment
[0118] FIG. 5 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a third embodiment of the present invention.
The third embodiment is a further modified example of the second
embodiment illustrated in FIG. 4. In FIG. 5, a device 500 differs
from the second embodiment in that it includes a concavo-convex
structure portion 541 that consists of a transparent resin and is
formed directly on the lower surface of the sealing substrate 102
without intervention of the adhesion layer, and a reflective layer
542 that is provided along the concavo-convex structure portion
541.
[0119] In the third embodiment, the concavo-convex structure
portion 541 serves as the structural layer X. Further, the surface
of the reflective layer 542 that is in contact with the
concavo-convex structure portion 541 serves as the reflective
surface of the reflective layer. In addition, the concavo-convex
structure portion 541 is the member that defines the concavo-convex
structure of the reflective surface of the reflective layer. With
such a configuration, the reflective layer 542 can also be
configured so as to have the specific concavo-convex structure of
the present invention. Therefore, with such a configuration, the
requirements of the present invention can be satisfied, and the
desired effect that are a high light extraction efficiency and
other effects can be obtained.
Fourth Embodiment
[0120] FIG. 6 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a fourth embodiment of the present invention.
As illustrated in FIG. 6, a light source device 600 of the fourth
embodiment includes a light-emitting element 620 formed by
stacking, on a substrate 601, a second transparent electrode layer
612, a light-emitting layer 621, and a first transparent electrode
layer 611 in this order, and a sealing substrate 602 that is
provided on the light-emitting element 620 via a sealing layer 631.
On the other hand, similar to the first embodiment, the reflective
layer 142 provided on the concavo-convex structure portion 141 of
the upper surface of the reflective portion composite substrate 140
is provided on the lower surface of the substrate 601 via the
adhesion layer 132. In the fourth embodiment, an upper surface 602A
of the sealing substrate 602 serves as the light-emitting surface
of the light source device. Further, similar to the first
embodiment, the adhesion layer 132 serves as the structural layer
X, and the face of the reflective layer 142 that is in contact with
the adhesion layer 132 serves as the reflective surface of the
reflective layer.
[0121] Thus, when the device is configured so that light is emitted
from the surface 602A of the sealing substrate 602, which is the
substrate on the opposite side to the substrate 601 on which the
light-emitting element is formed, the requirements of the present
invention (i.e., a configuration having a first transparent
electrode layer, a light-emitting layer, a second transparent
electrode layer, and a reflective layer having the specific
reflective surface in this order) can be satisfied. Consequently,
the requirements of the present invention can be satisfied, and the
desired effect that are a high light extraction efficiency and
other effects can be obtained. Although the refractive index of the
substrate 601 is not particularly limited, it is preferred that the
substrate have a high refractive index of 1.5 or more, and more
preferably of 1.6 or more. If a substrate having such a refractive
index is used, the lower limit for the refractive index of the
adhesion layer 132 (the structural layer X in this embodiment) is
preferably 1.5 or more, which is the same as the substrate, and
more preferably 1.6 or more. On the other hand, since the
refractive index does not have to be equal to or greater than the
refractive index of the light-emitting element, the upper limit for
the refractive index of the adhesion layer 132 is preferably 1.9 or
less.
Fifth Embodiment
[0122] FIG. 7 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a fifth embodiment of the present invention.
The fifth embodiment is a modified example of the first embodiment
illustrated in FIG. 1. In FIG. 7, a device 700 differs from the
first embodiment in that it has a sealing adhesion layer 732 in
place of the sealing layer 131, sealing substrate 102, and adhesion
layer 132, on the lower side of the second transparent electrode
layer 112. Specifically, in the fifth embodiment, the sealing
adhesion layer 732 is in direct contact with both the second
transparent electrode layer 112 and the reflective layer 142.
[0123] In the fifth embodiment, the sealing adhesion layer 732
serves as the structural layer X. Further, the surface of the
reflective layer 142 in contact with the sealing adhesion layer 732
serves as the reflective surface of the reflective layer.
[0124] In the fifth embodiment, instead of the sealing substrate
102, the reflective layer 142 blocks infiltration of oxygen,
moisture and the like in the air into the light-emitting element
120 (first transparent electrode layer 111, light-emitting layer
121, and second transparent electrode layer 112). Consequently,
deterioration can be prevented with a simpler layer configuration,
whereby a light source device that is thin and inexpensive and has
a long life can be obtained.
[0125] As in the fifth embodiment, when the reflective layer 142
functions as a barrier for blocking the okygen, moisture and the
like in the air, it is preferred that the material for forming the
reflective layer 142 includes a layer of a metal such as aluminum
and silver. Further, although this metal layer may be formed of a
single layer of one type of metal, the metal layer may also be
configured from a plurality of layers. In a reflective layer that
is configured from a plurality of layers, the respective layers
forming the reflective layer may be formed of the same metal or
from different metals. In addition, the reflective layer may also
be configured by stacking a functional layer of an inorganic thin
layer or an organic thin layer and a metal layer. It is more
preferred to, as described above, provide a silver layer on an
aluminum layer and use this silver layer as the reflective
surface.
[0126] From the perspective of securing a reflective performance
and a barrier performance, it is preferred that the thickness of
the reflective layer 142 is 0.1 to 10 .mu.m. Generally, when
sealing an organic EL light-emitting element with a metal layer, a
water vapor barrier property of 10.sup.-5 g/m.sup.2 per day or
lower is required. However, in the present invention, by
appropriately selecting the sealing adhesion layer and the
reflective portion composite substrate, a high barrier performance
can be obtained with a thin metal reflective layer that can be
easily produced. Further, although not illustrated in the drawing,
from the same perspective of securing a barrier performance, a
barrier layer may be formed between the sealing adhesion layer 732
and the transparent electrode layer 112. Examples of such a barrier
layer may include various metal oxides and metal nitrides, such as
SiO.sub.2, SiON, SiN, SiOC, and Al.sub.2O.sub.3. Although not
either illustrated in the drawing, instead of the sealing adhesion
layer 732, an energy beam curable resin such as an acrylate resin,
a methacrylate resin resin and the like, sticky-bonding function
resins and adhesive-bonding function resins of an acrylic type, an
olefinic type and the like, a thermofusion type adhesive-bonding
function resin that melts when heated and hardens when cooled, an
inactive liquid such as a fluorohydrocarbon, silicon oil and the
like, and liquid crystal material of nematic liquid crystals,
smectic liquid crystals and the like that can be used as a sealing
layer can be used. Particularly, employment of a material having
high fluidity facilitates the filling of the concavo-convex
structure of the reflective layer with the sealing layer.
[0127] It is preferred that the refractive index of the sealing
adhesion layer 732 (in the present embodiment, the structural layer
X) is equal to or greater than the refractive index of the
substrate and the sealing substrate. If the substrate and sealing
substrate are formed of an ordinary material such as a glass or a
film, the lower limit for the refractive index n of the sealing
adhesion layer 732 is preferably 1.5 or more, and more preferably
1.6 or more. On the other hand, since the refractive index does not
have to be equal to or greater than the refractive index of the
light-emitting element, the upper limit for the refractive index n
of the sealing adhesion layer 732 is preferably 1.9 or less.
Sixth Embodiment
[0128] FIG. 8 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a sixth embodiment of the present invention.
The sixth embodiment is a further modified example of the fifth
embodiment illustrated in FIG. 7. In FIG. 8, a device 800 differs
from the fifth embodiment in that it includes a transparent
concavo-convex layer 840 having a concavo-convex structure portion
841 formed on its lower surface, and a reflective layer 842
provided on the lower surface of the concavo-convex structure
portion 841 that is formed on the lower surface of the transparent
concavo-convex layer 840. The transparent concavo-convex layer 840
is provided on a lower side of the second transparent electrode
layer 112 via a sealing adhesion layer 832. In the sixth
embodiment, the transparent concavo-convex layer 840 serves as the
structural layer X. Further, the surface of the reflective layer
842 in contact with the concavo-convex structure portion 841 of the
transparent concavo-convex layer 840 serves as the reflective
surface of the reflective layer.
[0129] In the sixth embodiment, due to the reflective layer 842
being arranged along the concavo-convex structure of the
concavo-convex structure portion of the transparent concavo-convex
layer 840, the reflective layer 842 can have the specific
concavo-convex structure of the present invention, and, similar to
the fifth embodiment, the reflective layer can block oxygen,
moisture and the like in the air from infiltrating into the
light-emitting element. Consequently, with such a configuration,
the light extraction efficiency can be increased, and the resulting
light source device can be thin and inexpensive and have a long
life.
Seventh Embodiment
[0130] FIG. 9 is an elevated cross-sectional view schematically
illustrating a layer configuration of an organic EL light source
device according to a seventh embodiment of the present invention.
The seventh embodiment is a further modified example of the sixth
embodiment illustrated in FIG. 8. In FIG. 9, a device 900 differs
from the sixth embodiment in that it has a sealing metal layer 943
and a substrate 944 thereof on an even lower side of the reflective
layer 842 via a sealing layer 933. In the seventh embodiment, the
transparent concavo-convex layer 840 serves as the structural layer
X. Further, the surface of the reflective layer 842 in contact with
the concavo-convex structure portion 841 of the transparent
concavo-convex layer 840 serves as the reflective surface of the
reflective layer. The sealing layer 933, sealing metal layer 943,
and substrate 944 thereof are not involved in the passage or
reflection of light.
[0131] The material forming the reflective layer 842 and the
material forming the metal layer 943 may be the same or different.
Further, the thickness of these layers may be the same or
different. In the seventh embodiment, the provision of the separate
metal layer 943 in addition to the reflective layer 842 enables
employment of a layer having a high sealing performance as the
sealing metal layer 943 regardless of its reflectance performance,
whereby, even when a layer having a high reflectance performance
but a low sealing performance is used as the reflective layer 842,
the reflection performance can be increased and the oxygen,
moisture and the like in the air can be blocked from infiltrating
into the light-emitting element to a better extent than those in
the sixth embodiment. Consequently, with such a configuration, the
light extraction efficiency can be increased, and the resulting
light source device can be thin and inexpensive and have a long
life.
Other Modified Examples: Concavo-convex Structure
[0132] In the aforementioned embodiments, a periodic structure in
which quadrangular pyramid-shaped concavo-convex structure units
were continuously aligned in two directions was exemplified as the
concavo-convex structure of the reflective layer. However, the
concavo-convex structure of the present invention is not limited
thereto. The concavo-convex structure may be in a variety of forms
as long as the relationships of the refractive index of the
structural layer X, the inclination angle .theta..times.1 of the
concavo-convex structure units and the mean inclination angle of
the concavo-convex structure fall within the aforementioned
ranges.
[0133] In addition to the quadrangular pyramid shape described
above, the concavo-convex structure unit may also be depressions
and/or protrusions in any of a variety of shapes, such as an
arbitrary pyramid or prismoid shape, a shape formed by rounding a
pyramid apex and/or edges, a shape formed of a part of a sphere or
an oval sphere, and a combination of these shapes. Further, the
concavo-convex structure may also be configured by arranging a
plurality of concavo-convex structure units that have a columnar
shape, such as a part of a cylinder or a rectangular column so that
the longitudinal direction of these columnar shapes is directed in
the horizontal direction and parallel to each other.
[0134] Further, the concavo-convex structure is not limited to a
configuration in which the concavo-convex structure units are
arranged without gaps. The concavo-convex structure may be
configured of a plurality of concavo-convex structure units, which
are depressions and/or protrusion, and a flat portion provided in
gaps between these concavo-convex structure units.
[0135] Specific examples of the concavo-convex structure of the
reflective layer other than the example illustrated in FIGS. 2 and
3 will now be described hereinbelow by illustrating a reflective
portion composite substrate having a concavo-convex structure
corresponding thereto.
[0136] FIG. 11 is a perspective view schematically illustrating a
modified example of the reflective portion composite substrate 140
having the concavo-convex structure portion 141 of the first
embodiment. In FIG. 11, the concavo-convex structure of the
reflective portion composite substrate 24X is a structure in which
concavo-convex structure units 24Z, which are quadrangular pyramid
protrusions, are continuously provided in two directions in the
plane. In this example, the concavo-convex structure units 24Z have
four oblique faces 24A to 24D and an apex 24T. The angle between
each of the four oblique faces 24A to 24D and the horizontal plane
is the same. The bottom face of the quadrangular pyramid shape of
the concavo-convex structure units 24Z is a square. Bottom edges
24E of the quadrangular pyramid shape of the concavo-convex
structure units 24Z are in contact with the bottom edges of other
concavo-convex structure units 24Z. Consequently, the
concavo-convex structure units 24Z are continuously arranged
without any gaps on the concavo-convex structure.
[0137] FIG. 12 is a partial cross-sectional view illustrating a
concavo-convex structure unit 24Z of the reflective portion
composite substrate 240 illustrated in FIG. 11 along a plane that
passes through the line 3a parallel to the bottom edge 24E and that
is parallel to the Z axis direction. An angle .theta.24 between the
oblique faces 24B and 24D and the horizontal plane is an
inclination angle .theta..times.1 of the concavo-convex structure
unit 24Z. Further, since the shape of the concavo-convex structure
units 24Z is the same across the overall surface having the
concavo-convex structure of the concavo-convex structure portion
241, the inclination angle .theta.24 of the concavo-convex
structure unit 24Z is also the mean inclination angle
.theta..times.2 of the concavo-convex structure of the reflective
surface.
[0138] FIGS. 13, 14, and 15 are each a partial cross-sectional view
schematically illustrating a modified example of the concavo-convex
structure unit 14Z of the reflective portion composite substrate
140 having the concavo-convex structure portion 141 of the first
embodiment. In each of FIGS. 13, 14, and 15, a cross-section of the
reflective portion composite substrate 34X, 44X, or 54X is a
partial cross-sectional view illustrating a cross-section of one
concavo-convex structure unit, similar to the cross-section of the
reflective portion composite substrate 140 illustrated in FIG.
3.
[0139] In FIG. 13, a concavo-convex structure unit 34Z of the
reflective portion composite substrate 34X has a shape formed by
combining a square quadrangular pyramid that has four oblique faces
including oblique faces 34F and 34H and an apex 34T with a shape of
a square quadrangular prismoid that has four oblique faces
including oblique faces 34B and 34D from which the plateau portion
has been removed. With such a shape, the angle between the oblique
face 34F or 34H and the horizontal plane, i.e. the greatest angle
among those for all the oblique faces, is employed as the
inclination angle .theta..times.1 of the concavo-convex structure.
Further, the mean inclination angle .theta..times.2 is determined
based on the aforementioned formula (5).
[0140] In FIG. 14, a concavo-convex structure unit 44Z of the
reflective portion composite substrate 44X is formed of a curved
face including an oblique face 44B. With such a shape, the greatest
angle among all the angles formed between the horizontal plane and
the curved face, i.e. the angle .theta.44 between a horizontal
plane and a tangent 44Q at a portion 44P where the angle of the
oblique face 44B is at its greatest, is employed as the inclination
angle .theta..times.1 of the concavo-convex structure. Further, the
mean inclination angle .theta..times.2 is determined based on the
aforementioned formula (5).
[0141] In FIG. 15, a concavo-convex structure unit 54Z of the
reflective portion composite substrate 54X has a prismoid shape
formed by combining a shape of a square quadrangular prismoid from
which the apex portion has been removed that has four oblique faces
including oblique faces 54B and 54D, with a surface 54T of a
horizontal square. With such a shape, the angle between the oblique
face 54B or 54D and the horizontal plane, i.e. the greatest angle
among those for all the oblique faces, is employed as the
inclination angle .theta..times.1 of the concavo-convex
structure.
[0142] Further, the mean inclination angle .theta..times.2 is
determined based on the aforementioned formula (5).
[0143] FIGS. 16 and 17 are each a perspective view schematically
illustrating another modified example of the reflective portion
composite substrate 140 having the concavo-convex structure portion
141 of the first embodiment. In FIG. 16, the concavo-convex
structure of the reflective portion composite substrate 64X has the
same concavo-convex structure units 14Z as those of the first
embodiment. In the reflective portion composite substrate 140, the
concavo-convex structure units 14Z are arranged without gaps in the
X and Y axis directions. However, in the reflective portion
composite substrate 64X, gaps 64J and 64K are provided between the
concavo-convex structure units 14Z in both the X and Y axis
directions, respectively.
[0144] With such a shape, the inclination angle .theta..times.1 of
the concavo-convex structure is the same as that of the reflective
portion composite 140. Further, the mean inclination angle
.theta..times.2 is determined based on the aforementioned formula
(5). In addition, the mean inclination angle is determined
excluding the flat portions.
[0145] In FIG. 17, the concavo-convex structure of the reflective
portion composite substrate 74X has the same concavo-convex
structure units 14Z as those of the first embodiment. In the
reflective portion composite substrate 74X, the concavo-convex
structure units 14Z are arranged continuously without gaps in the Y
axis direction. However, in the X axis direction, the
concavo-convex structure units 14Z are not arranged continuously,
and a gap 74J is provided. With such a shape, the inclination angle
.theta..times.1 of the concavo-convex structure is the same as that
of the reflective portion composite 140. Further, the mean
inclination angle .theta..times.2 is determined based on the
aforementioned formula (5).
[0146] Further modified examples of the reflective portion
composite substrate may include those having structures obtained by
effecting modification on the structures other than the
depression-shaped concavo-convex structure units 14Z illustrated in
FIG. 2, wherein the modification is to inverse the units 14Z to
obtain the protrusion-shaped concavo-convex structure units 24Z
illustrated in FIG. 11. For example, such examples may include
those having structures obtained by inversion of the
depression-shaped concavo-convex structure units 34Z, 44Z, 54Z,
64Z, and 74Z in the reflective portion composite substrates 34X,
44X, 54X, 64X, and 74X illustrated in FIGS. 12 to 17, to form
protrusion-shaped concavo-convex structure units.
[0147] In addition, when the shape of the reflective surface is
defined by a member that is above the reflective layer (transparent
concavo-convex layer, concavo-convex structure member directly
provided on a lower side of the sealing substrate etc.) as
described in the second, third, sixth, and seventh embodiments
illustrated in FIGS. 4, 5, 8, and 9, the member may have the same
structures as the aforementioned structures of the reflective
portion composite substrates. For example, in the second embodiment
illustrated in FIG. 4, a structure having the same concavo-convex
structure as the reflective portion composite substrate 140
illustrated in FIG. 2 may be employed as the transparent
concavo-convex layer 440. In this case, the concavo-convex
structure of the reflective surface has the inversed structure of
that of the first embodiment (this is because in the first
embodiment the reflective portion composite substrate 140 is on the
lower side of the reflective surface, whereas in the second
embodiment the transparent concavo-convex layer 440 is on the upper
side).
[0148] In the examples illustrated as the reflective portion
composite substrates 64X and 74X illustrated in FIGS. 16 and 17,
the concavo-convex structure on the surface of the member that
defines the concavo-convex structure of the reflective surface,
such as the reflective portion composite substrate or the
transparent concavo- convex layer, has depression-shaped
concavo-convex structure units provided apart from each other and
flat gap portions between the concavo-convex structure units. These
examples are preferred from the perspective of increasing the
mechanical strength of the light source device during production
and use. By providing such a structure, it is possible to provide a
reflective surface concavo-convex structure capable of achieving
effective prevention of deterioration of the concavo-convex
structure due to abrasion during production and use, and also
achieving a good light extraction efficiency.
[0149] Although the height of the concavo-convex structure of the
reflective surface of the reflective layer is not particularly
limited, it is particularly preferred that this height is 0.3 to
100 .mu.m as the difference between the highest portion and the
lowest portion (for example, in the example illustrated in FIG. 3,
the height indicated by arrow 14H).
(Use)
[0150] Use of the organic EL light source device of the present
invention is not particularly limited, although the device may be
used as a light source for a backlight for a liquid crystal display
device, an illumination device and the like that utilize
advantageous effects of the invention, such as a high light
extraction efficiency.
[0151] The light source device of the present invention is not
limited to the embodiments specifically described above, and the
light source devices falling within the scope of the patent claims
and equivalents thereof are encompassed by the present invention.
For example, the light source device of the present invention
includes the first transparent electrode layer, light-emitting
layer, second transparent electrode layer, structural layer X, and
reflective layer as essential components. However, the light source
device of the present invention may also include an optional layer
as an optional component other than the aforementioned diffusion
plate, sealing layer, reflective portion composite substrate and
the like. The optional layer may be between those layers, at a
position closer to the light-emitting surface than the first
transparent electrode layer, or at a position further away from the
light-emitting surface than the reflective layer (opposite side to
the light-emitting surface). Further, in addition to the substrate
and sealing substrate and a layer such as a sealing layer above and
below the light-emitting element that were mentioned as examples of
the structure for sealing the light-emitting element, the light
source device of the present invention may also include a sealing
member for sealing the peripheral region of the light-emitting
element. In addition, the light source device may also include
other optional components required for forming the light source
device, such as electricity distribution means for supplying the
electrodes with electricity.
EXAMPLES
[0152] The present invention will now be described in more detail
based on the examples. However, the present invention is not
limited to the following examples.
Preparatory Example 1
[0153] Preparation of Adhesive for Sealing Layer
[0154] 300 parts by weight of polyisoprene was completely dissolved
in 700 parts by weight of toluene, and 2.4 parts by weight of
p-toluenesulfonic acid was added thereto, for carrying out a
cyclization reaction to obtain a solution of a polymer cyclized
product.
[0155] 2.5 parts by weight of maleic anhydride was added to 100
parts by weight of the obtained polymer cyclized product in the
solution for carrying out an addition reaction.
[0156] A part of the toluene in the solution was removed by
distillation, and an antioxidant was added thereto. Then vacuum
drying was carried out for removing the toluene and unreacted
maleic anhydride, to obtain a modified conjugated diene polymer
cyclized product type adhesive.
Example 1
[0157] An organic EL light source device having the configuration
of the first embodiment illustrated in FIG. 1 was produced. [0158]
1-1: Preparation of Light-Emitting Element
[0159] On a surface of a 0.7 mm-thick glass substrate 101, an
organic EL light-emitting element that included the first
transparent electrode layer 111, the organic light-emitting layer
121, and the second transparent electrode layer 112 was provided.
[0160] 1-2: Preparation of Stacked Body in which Light-Emitting
Element is Sealed
[0161] A surface of a 0.7 mm-thick glass sealing substrate 102 was
coated with the adhesive for a sealing layer obtained in
Preparatory Example 1. This coated surface was attached to the
surface on the second transparent electrode layer side of the
light-emitting element obtained in (1-1). Electricity distribution
means to the electrode layer was provided on the peripheral region
of the element, and the element was then sealed with a periphery
sealing member (not illustrated in FIG. 1) to form a 15 .mu.m-thick
sealing layer 131. As a result, a stacked body having the substrate
101, the first transparent electrode layer 111, the organic
light-emitting layer 121, the second transparent electrode layer
112, the sealing layer 131, and the sealing substrate 102 was
obtained. [0162] 1-3: Reflective Portion Composite Substrate
[0163] A surface of a substrate film formed of a resin having an
alicyclic structure (Trade name: "ZEONOR Film", manufactured by
ZEON CORPORATION) was coated with a UV-ray curable resin (acrylate
resin, refractive index n=1.53) to form a coating layer. A metal
mold having a predetermined shape was pressed against the coating
layer, and UV-ray irradiation was performed at a cumulative light
amount of 1,000 mJ/cm.sup.2 from the substrate film side to cure
the coating layer, to form a concavo-convex structure portion on
the substrate film. Then, the mold was peeled off the
concavo-convex structure portion, to obtain a reflective portion
composite substrate 140 composed of the substrate film and the
concavo-convex structure portion.
[0164] The concavo-convex structure on the surface of the
concavo-convex structure portion of the obtained reflective portion
composite substrate 140 was composed of the plurality of
quadrangular pyramid shaped depressions 14Z schematically
illustrated in FIG. 2. The angle between the oblique faces 14A to
14D constituting the depressions 14Z and the surface of the
substrate film was 30.degree.. The length of the bottom edge 14E of
the depressions 14Z was 20 .mu.m. The depressions 14Z were aligned
with a pitch of 20 .mu.m in two directions orthogonal to each other
on the plane of the concavo-convex structure portion. The total
thickness of the reflective portion composite substrate 140 was 200
.mu.m. [0165] 1-4: Reflective Layer having Concavo-Convex
Structure
[0166] On the surface on which the ridges were formed of the
reflective portion composite substrate 140 obtained in (1-3), vapor
deposition of silver was performed to a thickness of 200 nm, to
form a metal reflective layer, whereby a reflective portion
composite body 144 composed of the reflective portion composite
substrate 140 and the reflective layer 142 having the
concavo-convex structure was obtained. [0167] 1-5: Production of
Light Source Device
[0168] The surface on the reflective layer 142 side of the
reflective portion composite body 144 obtained in (1-4) was coated
with the sealing adhesive obtained in Preparatory Example 1, and
this coated surface was attached to the sealing substrate 102 side
of the stacked body obtained in (1-2), to form an adhesion layer
132 having a thickness (distance from the highest portion of the
reflective surface concavo-convex structure to the sealing
substrate 102) of 18 .mu.m. As a result, an organic EL light source
device having the substrate 101, the first transparent electrode
layer 111, the organic light-emitting layer 121, the second
transparent electrode layer 112, the sealing layer 131, the sealing
substrate 102, the adhesion layer 132, the reflective layer 142,
and the reflective portion composite substrate 140 was obtained.
The refractive indices of the sealing layer 131 and the adhesion
layer 132 were both 1.5.
[0169] In the present example, since the adhesion layer 132 serves
as the structural layer X, in expressions (1) to (4) n is 1.5. That
is, according to expression (1) .theta..times.1.ltoreq.41.8,
according to expression (2)
16.1.ltoreq..theta..times.2.ltoreq.41.8, according to expression
(3) 24.1.ltoreq..theta..times.2.ltoreq.42.8, and according to
expression (4) 28.0.ltoreq..theta..times.2.ltoreq.38.0. Further, in
the present example, .theta..times.1 and .theta..times.2 are both
30.degree.. Consequently, the present example satisfies these
expressions (1) to (4). [0170] 1-6: Evaluation
[0171] Light was emitted by applying a constant current to the
obtained organic EL light source device. Luminosity was measured
using an EZ-contrast manufactured by ELDIM to determine the total
light amount.
Comparative Example 1
[0172] An organic EL light source device was produced in the same
manner as in Example 1, except for changing the mold in step (1-3).
In the obtained organic EL light source device, the concavo-convex
structure on the surface of the concavo-convex structure portion of
the reflective portion composite substrate 140 was composed of the
plurality of quadrangular pyramid shaped depressions 14Z
schematically illustrated in FIG. 2. The angle between the oblique
faces 14A to 14D forming the depressions 14Z and the surface of the
substrate film was 60.degree.. The length of the bottom edge 14E of
the depressions 14Z was 20 .mu.m. The depressions 14Z were aligned
with a pitch of 20 .mu.m in two directions orthogonal to each other
on the surface of the concavo-convex structure portion. The total
thickness of the reflective portion composite substrate 140 was 200
.mu.m.
[0173] In the present comparative example, the adhesion layer 132
serves as the structural layer X, so that in expressions (1) to (4)
n is 1.5. That is, according to expression (1)
.theta..times.1.ltoreq.41.8, according to expression (2) 16.1
.ltoreq..theta..times.2.ltoreq.41.8, according to expression (3)
24.1.ltoreq..theta..times.2.ltoreq.41.8, and according to
expression (4) 28.0.ltoreq..theta..times.2.ltoreq.38.0. Further, in
the present example, .theta..times.1 and .theta..times.2 are both
60.degree.. Consequently, the present comparative example does not
satisfy the expressions (1) to (4).
[0174] Light was emitted by applying a constant current to the
obtained organic EL light source device. Luminosity was measured
using an EZ-contrast manufactured by ELDIM to determine the total
light amount. It was thus found out that Example 1 had an 11%
larger total light amount than Comparative Example 1.
Example 2
[0175] The relationship between the mean inclination angle)
(.degree.) of the oblique faces in a quadrangular pyramid and the
light extraction efficiency (%) from a light-emitting surface 100A
was studied based on a simulation using a program (Program name:
Light Tools, Optical Research Associates) in the following case. In
the organic EL light source device illustrated in FIG. 1, the
refractive indices of the light-emitting layer 121 and second
transparent electrode layer (ITO) were set to 1.8, the refractive
indices of the sealing layer 131 and adhesion layer 132 were set to
1.53, the refractive indices of the substrate 101 and sealing
substrate 102 were set to 1.53, the reflectance of the reflective
surface of the reflective layer 142 was set to 100%, and the
optical density of the light-emitting element 120 is set to a value
with which the light that passes through the light-emitting element
120 from the front direction is absorbed with the absorbance ratio
of 10%. The shape of the concavo-convex structure units of the
reflective surface is set to the quadrangular pyramid shape
illustrated in FIG. 2. The orientation characteristic (initial
orientation characteristic) of the light emitted from the
light-emitting element 120 toward the substrate 101 and the sealing
layer 131 is set as described below. The results of study are shown
in Table 18.
[0176] Initial orientation characteristic: Luminosity
(.theta.)=1
[0177] Here, .theta. is the angle (.degree.) between the normal
direction of the main plane of the light-emitting layer and the
observing direction, and luminosity (.theta.) represents the
luminosity when observed from this angle.
[0178] In the present example, since the adhesion layer serves as
the structural layer X, in expressions (1) to (4) n is 1.53. That
is, according to expression (1) .theta..times..ltoreq.40.8,
according to expression (2)
16.4.ltoreq..theta..times.2.ltoreq.40.8, according to expression
(3) 24.6.ltoreq..theta..times.2.ltoreq.40.8, and according to
expression (4) 27.7.ltoreq..theta..times.2.ltoreq.37.7. Further, in
the present example, both .theta..times.1 and .theta..times.2 match
the mean inclination angle.
[0179] From the results in FIG. 18, it can be seen that when the
mean inclination angle is varied, a preferred extraction efficiency
can be obtained when expressions (1) and (2) are satisfied, a more
preferred extraction efficiency can be obtained when expression (3)
is satisfied, and an even more preferred extraction efficiency can
be obtained when expression (4) is satisfied.
Reference Example 1
[0180] The reflectance of a reflective surface when a metal layer
was employed for the reflective layer was calculated. For the
calculation, the refractive index of aluminum was set as 1.29, the
complex refractive index of aluminum was set as 7.23, the
refractive index of silver was set as 0.13, and the complex
refractive index of silver was set as 3.34. Studies were performed
as to three instances that are: (i) an instance in which silver was
used as the reflective layer, (ii) an instance in which aluminum
was used as the reflective layer, and (iii) an instance in which
aluminum and silver were used as the reflective layer, with the
layer configured so that the silver served as the reflective
surface. In each of (i) and (ii), the layer thickness of the
reflective layer for both of (i) and (ii) was varied. In (iii), the
aluminum layer thickness in (iii) was set to 100 nm and the silver
layer thickness was varied. FIG. 19 shows the results of study of
the relationship between layer thickness and reflectance.
[0181] From the results in FIG. 19, it can be seen that in the
instance (ii), reflectance reached saturation at under 90%, and it
was unable to obtain a reflectance as high as that in the instance
(i) even when the layer thickness was increased. On the other hand,
in the instance (iii), it was possible to obtain a high reflectance
comparable to that of the thick silver reflective layer of (i) at a
silver thickness of about 50 nm. Based on these results, it can be
seen that in the instance (iii) a reflective layer having a low
total cost and a high reflectance can be obtained using a layer
formed of low-cost aluminum and a small amount of high-cost
silver.
Reference Example 2
[0182] Based on the results of study of Reference Example 1, (i) a
100 nm silver reflective layer, (ii) a 100 nm aluminum reflective
layer, and (iii) a combination of 100 nm aluminum and 20 nm silver
in which silver is served as the reflective surface, were produced
and the reflectance of each reflective layer was measured. The
results were 98.8% for (i), 88.3% for (ii), and 94.2% for
(iii).
Reference Signs List
[0183] 100, 400, 500, 600, 700, 800, 900 Organic EL Light Source
Device
[0184] 101, 601 Substrate
[0185] 102, 602 Sealing Substrate
[0186] 111, 611 First Transparent Electrode Layer
[0187] 112, 612 Second Transparent Electrode Layer
[0188] 120, 620 Light-emitting Element
[0189] 121, 621 Light-emitting Layer
[0190] 131, 631, 933 Sealing Layer
[0191] 132, 432 Adhesion Layer
[0192] 140, 24X, 34X, 44X, 54X, 64X, 74X Reflective Portion
Composite Substrate
[0193] 141, 441, 541, 841 Concavo-convex Structure Portion
[0194] 142, 442, 542, 842 Reflective Layer
[0195] 144 Reflective Portion Composite Body
[0196] 14A-14D, 24A-24D, 34B, 34D, 34F, 34H, 44B, 54B, 54D Oblique
Face
[0197] 14E, 24E Bottom Edge
[0198] 14T, 24T, 34T Apex
[0199] 14Z, 24Z, 34Z, 44Z, 54Z Concavo-convex Structure Unit
[0200] 440, 840 Transparent Concavo-convex Layer
[0201] 54T Flat Surface
[0202] 64J, 64K, 74J Gap
[0203] 732, 832 Sealing Adhesion Layer
[0204] 943 Sealing Metal Layer
[0205] 944 Substrate
* * * * *